Transductin-1 and applications to hereditary deafness

ABSTRACT

The invention provides methods of detecting hearing loss or a predisposition to hearing loss in an animal, which comprises detecting at least one mutation in a gene encoding transduction-1 (TDC1) in a test sample obtained from the animal. The invention also provides a method of determining the level of nucleic acid comprising a wild-type TDC1 gene and/or a mutant TDC1 gene in a test sample obtained from an animal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national phase of PCT/US02/29614, which wasfiled on Sep. 19, 2002 and which claims the benefit of U.S. provisionalpatent application no. 60/323,275 which was filed on Sep. 19, 2001.

FIELD OF THE INVENTION

The present invention pertains to isolated or purified nucleic acidsencoding transductin-1 (TDC1; now referred to as transmembranecochlear-expressed gene 1 (TMC-1)), transductin-2 (TDC2; now referred toas transmembrane cochlear-expressed gene 2 (TMC2)), and fragmentsthereof, a vector comprising such a nucleic acid, a cell comprising sucha vector, an isolated or purified polypeptide, a monoclonalantibody-producing cell line, a monoclonal antibody, pharmaceuticallyacceptable compositions of the above nucleic acids and polypeptides, andmethods of diagnosis, prognosis and treatment of hearing loss,particularly DFNA 36 and DFNB 7/11-linked hearing loss.

BACKGROUND OF THE INVENTION

Hearing loss is a common communication disorder. Congenital hearingimpairment occurs in approximately 1 in 1,000 children born in theUnited States. See Jain et al., A human recessive neurosensorynonsyndromic hearing impairment locus is a potential homologue of themurine deafness (dn) locus, Human Molecular Genetics 4(12): 2391–2394(1995); and Scott et al., Refining the DFNB7-DFNB11 deafness locus usingintragenic polymorphisms in a novel gene, TMEM2, Gene 246: 265–274(2000). One to two percent of graduates of neonatal intensive care unitsalso suffer such hearing impairment. See Jain et al. (1995), supra.Nearly 1 in 2 adults have functionally significant hearing loss by theeighth decade of life.

Deafness can be caused by a number of environmental and disease-relatedfactors. In developed countries, however, at least 50% of the cases ofdeafness are inherited. See Scott et al. (2000), supra. Factorsassociated with an increased risk for hearing loss include male gender,exposure to aminoglycoside antibiotics, exposure to noise, head trauma,and barotraumas. The majority of cases seem to involve single genemutations, as there is no additional clinical anomaly, and an autosomalrecessive mode of inheritance predominates. Nonsyndromic hereditaryhearing impairment (NSHHI) is considered to be highly heterogeneous, andis thought to be caused by a large number of genes.

Vertebrates detect sounds, body accelerations and water movements withthe acoustico-lateralis sensory system (Hudspeth et al., Sensitivity,polarity, and conductance change in the response of vertebrate haircells to controlled mechanical stimuli, Proc. Natl. Acad. Sci. USA74(6): 2407–2411 (1977)). The primary receptors of this system areneuroepithelial cells termed hair cells. Each of these cells has a “hairbundle” on its apical surface, which is comprised of an elongatedmicrovillus (stereocilium) and, in most cases, a single true cilium(kinocilium). Vibrations, such as from sound waves, stimulate the cellsby bending the hair bundles. Bending of the hair bundles leads to theproduction of a small receptor potential, which excites afferent nervefibers by chemical or electrical synapses. The exact mechanism of theproduction of the potential is not yet known, with the existence ofconflicting data as to the ions involved in creating the potential(Corey et al., Ionic basis of the receptor potential in a vertebratehair cell, Nature 281: 675–77 (1979)).

Thus far, linkage studies have been the primary method employed toidentify potential loci implicated in hereditary deafness. However,single families suitable in size for conventional linkage analysis arenot common. NSHHI also lends itself poorly to subclassification byaudiometric criteria. Thus, traditional studies have used consanguineousfamilies from geographically isolated populations to map severaldifferent loci which are associated with recessive NSHHI (Jain et al.(1995), supra). In humans certain forms of NSHHI have been found tolocalize to a region of chromosome 9. See, e.g. Kurima et al., Geneticmap localization of DFNA34 and DFNA36, two novel autosomal dominantnonsyndromic deafness loci, ARO Abstracts 24:265 (2001); and Scott etal. (2000), supra. Scott et al. identified a gene in the relevant regionof the chromosome; however, it was poorly correlated to hearing loss atthe particular locus, as the protein was expressed in a variety of othertissues, such as the heart, brain, spleen, lung, liver, muscle andkidney, and no difference in transcript size or expression level wasapparent between normal and deaf mice by Northern blot analysis.

In view of the above, it is an object of the present invention toprovide a gene that correlates well with hearing loss as well as theencoded polypeptide and related vectors, host cells, polypeptides,antibodies, antibody-producing cell lines and methods of diagnosing,prognosticating and treating hearing loss. These and other objects andadvantages of the present invention, as well as additional inventivefeatures, will be apparent from the description of the inventionprovided herein.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an isolated or purified nucleic acidmolecule consisting essentially of a nucleotide sequence encoding TDC1or a fragment thereof comprising at least 314 contiguous nucleotides,and an isolated or purified nucleic acid molecule consisting essentiallyof a nucleotide sequence that is complementary to a nucleotide sequenceencoding human TDC1 or a fragment thereof.

The present invention further provides an isolated or purified nucleicacid molecule consisting essentially of a nucleotide sequence encodingTDC2 or a fragment thereof comprising at least 110 contiguousnucleotides, and an isolated or purified nucleic acid moleculeconsisting essentially of a nucleotide sequence that is complementary toa nucleotide sequence encoding human TDC2 or a fragment thereof.

Also provided by the present invention is a vector comprising one of theabove-described isolated or purified nucleic acid molecules. Furtherprovided is a cell comprising one of the above-identified nucleic acidmolecules. Also provided is a composition comprising one of the aboveidentified isolated or purified nucleic acid molecules or vectors and apharmaceutically acceptable carrier.

An isolated or purified polypeptide molecule consisting essentially ofan amino acid sequence encoding TDC1 or a fragment thereof comprising atleast 95 contiguous amino acids, which is optionally glycoslyated,amidated, carboxylated, phosphorylated, esterified, N-acylated orconverted into an acid addition salt, is also provided.

An isolated or purified polypeptide molecule consisting essentially ofan amino acid sequence encoding TDC2 or a fragment thereof comprising atleast 71 contiguous amino acids, which is optionally glycoslyated,amidated, carboxylated, phosphorylated, esterified, N-acylated orconverted into an acid addition salt, is further provided.

Also provided is a composition comprising an above-described isolated orpurified polypeptide molecule and a pharmaceutically acceptable carrier.Further provided is a cell line that produces a monoclonal antibody thatis specific for an above-described isolated or purified polypeptidemolecule. Still further provided is the antibody produced by theabove-mentioned cell-line.

Methods of detecting hearing loss or a predisposition to hearing loss inan animal are also provided. In one embodiment, the method comprisesdetecting at least one mutation in a gene encoding TDC1 in a test samplecomprising a nucleic acid comprising the TDC1 gene obtained from theanimal, wherein the at least one mutation is indicative of hearing lossor a predisposition to hearing loss in the animal. The hair cell can beof the inner ear of the animal. In another embodiment, the methodcomprises detecting at least one mutation in a gene encoding TDC2 in atest sample comprising a nucleic acid comprising the TDC2 gene obtainedfrom the animal, wherein the at least one mutation is indicative ofhearing loss or a predisposition to hearing loss in the animal.

Also provided is a method of determining the level of nucleic acidcomprising the wild-type TDC1 gene and/or a mutant TDC1 gene in a testsample comprising a nucleic acid comprising the wild-type TDC1 geneand/or a mutant TDC1 gene obtained from an animal. The method comprisesassaying the test sample for the level of nucleic acid comprising thewild-type TDC1 gene and/or a mutant TDC1 gene, wherein a decrease in thelevel of nucleic acid comprising the wild-type TDC1 gene and/or anincrease in the level of nucleic acid comprising a mutant TDC1 gene inthe test sample as compared to a control sample is indicative of hearingloss or a predisposition to hearing loss in the animal. The method canbe used to prognosticate hearing loss or to assess the efficacy oftreatment of hearing loss with a given anti-hearing loss agent inaccordance with methods set forth herein.

Further provided is a method of determining the level of nucleic acidcomprising the wild-type TDC2 gene and/or a mutant TDC2 gene in a testsample comprising a nucleic acid comprising the wild-type TDC2 geneand/or a mutant TDC2 gene obtained from an animal. The method comprisesassaying the test sample for the level of nucleic acid comprising thewild-type TDC2 gene and/or a mutant TDC2 gene, wherein a decrease in thelevel of nucleic acid comprising the wild-type TDC2 gene and/or anincrease in the level of nucleic acid comprising a mutant TDC2 gene inthe test sample as compared to a control sample is indicative of hearingloss or a predisposition to hearing loss in the animal. The method canbe used to prognosticate hearing loss or to assess the efficacy oftreatment of hearing loss with a given anti-hearing loss agent inaccordance with methods set forth herein.

Methods for detecting hearing loss or a predisposition to hearing lossin an animal are also provided. In one embodiment, the method comprisesdetecting a mutant TDC1 in a test sample comprising protein comprisingTDC1 obtained from the animal, wherein the presence of a mutant TDC1 inthe test sample is indicative of hearing loss or a predisposition tohearing loss in the animal. In another embodiment, the method comprisesdetecting a mutant TDC2 in a test sample comprising protein comprisingTDC2 obtained from the animal, wherein the presence of a mutant TDC2 inthe test sample is indicative of hearing loss or a predisposition tohearing loss in the animal.

Also provided is a method of determining the level of wild-type TDC1and/or a mutant TDC1 in a test sample comprising protein comprisingwild-type TDC1 and/or a mutant TDC1 obtained from an animal. The methodcomprises assaying the test sample for the level of wild-type TDC1and/or a mutant TDC1, wherein a decrease in the level of wild-type TDC1and/or an increase in the level of a mutant TDC1 in the test sample ascompared to a control sample is indicative of hearing loss or apredisposition to hearing loss in the animal. The method can be used toprognosticate hearing loss or to assess the efficacy of treatment ofhearing loss with a given anti-hearing loss agent in accordance withmethods set forth herein.

Also provided is a method of determining the level of wild-type TDC2and/or a mutant TDC2 in a test sample comprising protein comprisingwild-type TDC2 and/or a mutant TDC2 obtained from an animal. The methodcomprises assaying the test sample for the level of wild-type TDC2and/or a mutant TDC2, wherein a decrease in the level of wild-type TDC2and/or an increase in the level of a mutant TDC2 in the test sample ascompared to a control sample is indicative of hearing loss or apredisposition to hearing loss in the animal. The method can be used toprognosticate hearing loss or to assess the efficacy of treatment ofhearing loss with a given anti-hearing loss agent in accordance withmethods set forth herein.

The invention further provides a method of treating an animalprophylactically or therapeutically for hearing loss, wherein thehearing loss is due to a complete or partial loss of wild-type TDC1,which method comprises providing TDC1 to the animal, whereupon theanimal is treated prophylactically or therapeutically for hearing loss.The TDC1 can be provided to the animal by administering to the animal anucleic acid encoding and expressing wild-type TDC1. The TDC1 also canbe provided to the animal by administering to the animal the wild-typeTDC1 protein.

The invention still further provides a method of treating an animalprophylactically or therapeutically for hearing loss, wherein thehearing loss is due to a complete or partial loss of wild-type TDC2,which method comprises providing TDC2 to the animal, whereupon theanimal is treated prophylactically or therapeutically for hearing loss.The TDC2 can be provided to the animal by administering to the animal anucleic acid encoding and expressing wild-type TDC2. The TDC2 also canbe provided to the animal by administering to the animal the wild-typeTDC2 protein.

Further provided is a method of identifying one or more agents whichinteract with a TDC1 gene and/or a TDC2 gene in a cell, comprisingadministering one or more agents to the cell comprising the TDC1 geneand/or the TDC2 gene and assaying the expression level of the TDC1 geneand/or the TDC2 gene by the cell, wherein an increase or decrease in theexpression level of the TDC1 gene and/or the TDC2 gene is indicative ofan interaction between one or more agents and the TDC1 gene and/or theTDC2 gene in the cell.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 represents the nucleotide (SEQ ID NO: 1) and deduced amino acid(SEQ ID NO: 2) full-length sequences of human TDC1 cDNA.

FIG. 2 represents the nucleotide (SEQ ID NO: 3) and deduced amino acid(SEQ ID NO: 4) full-length sequences of human TDC2 cDNA.

FIG. 3 represents the nucleotide (SEQ ID NO: 5) and deduced amino acid(SEQ ID NO: 6) full-length sequences of mouse TDC1 cDNA.

FIG. 4 represents the nucleotide (SEQ ID NO: 7) and deduced amino acid(SEQ ID NO: 8) full-length sequences of mouse TDC2 cDNA.

DETAILED DESCRIPTION OF THE INVENTION

The TDC1 and TDC2 genes are implicated in DFNA 36- and DFNB 7/11-linkedhearing loss, two forms of hereditary deafness. These genes also may be,at least in part, the cause of certain forms of non-hereditary deafness,or other forms of hereditary deafness. These genes encode amechanotransduction channel of an animal hair cell, particularly haircells of the inner ear. These cells are responsible for turningmechanical stimulation (such as sound waves) into chemical signals whichcan be processed by the brain. Any abnormality in the normal expressionof this mechanotransduction channel can lead to hearing loss. Thisabnormal expression may result from mutations or deletions in thesequence or in the sequences surrounding the particular gene, or fromother genetic abnormalities as are known in the art. Particularly, themutation(s) can compromise the ability of the TDC1 and/or TDC2 geneproduct to form a component of a hair cell of the inner ear of theanimal, thereby causing hearing loss. The mutation(s) can alsocompromise the ability of the TDC1 and/or TDC2 gene product to form allor some of an ion transduction channel of the hair cell of the inner earof the animal. Further, the mutation(s) can compromise themechanosensory activity of the TDC1 and/or TDC2 gene product. Hearingloss can mean either the entire loss or partial loss of hearing as wouldbe understood by an ordinarily skilled artisan. The hearing loss can behereditary, sensorineural hearing loss, nonsyndromic autosomal-dominanthearing loss, and/or DFNA 36- or DFNB 7/11-linked hearing loss.

Mutations in TDC1 and/or TDC2 can cause deafness. In particular,dominant mutations can cause childhood-onset, rapidly progressive,bilateral sensorineural hearing loss. Several recessive mutations cancause congenital, profound bilateral sensorineural deafness. Several ofthe recessive mutations can also result in functional null alleles:nonsense mutations, genomic deletion of two exons, or frameshiftmutations.

Any animal with hair cells within their auditory receptor can benefitfrom the present invention. Desirably, the animal is a mammal,preferably a human. However, animals such as birds, especially chickens,also can benefit from the present invention.

The present invention provides an isolated or purified nucleic acidmolecule consisting essentially of a nucleotide sequence encodingtransductin or a fragment thereof. By transductin is meant TDC1 and/orTDC2, preferably of an animal, and even more preferably of a human. By“isolated” is meant the removal of transductin from its naturalenvironment. By “purified” is meant that transductin, whether it hasbeen removed from nature or synthesized and/or amplified underlaboratory conditions, has been increased in purity, wherein “purity” isa relative term, not “absolute purity.” “Nucleic acid molecule” isintended to encompass a polymer of DNA or RNA, i.e., a polynucleotide,which can be single-stranded or double-stranded and which can containnon-natural or altered nucleotides. Moreover, the nucleic acids andgenes can comprise exons, introns, and/or regulatory regions andelements.

Preferably, the isolated or purified nucleic acid molecule consistsessentially of a nucleotide sequence encoding TDC1 or a fragment thereofcomprising at least 314 contiguous nucleotides. The TDC1 can be a humanTDC1. In a preferred embodiment, the isolated or purified nucleic acidmolecule can encode the amino acid sequence of SEQ ID NO: 2 or afragment thereof comprising at least 105 contiguous amino acids. Morepreferably, the fragment comprises at least 110 contiguous amino acids.Still more preferably, the fragment comprises at least 115 contiguousamino acids. Even more preferably, the fragment comprises at least 120contiguous amino acids. Alternatively, the isolated or purified nucleicacid molecule consists essentially of the nucleotide sequence of SEQ IDNO: 1 or a fragment thereof comprising at least 314 contiguousnucleotides. More preferably, the fragment comprises at least 320contiguous nucleotides. Still more preferably, the fragment comprises atleast 330 contiguous nucleotides. Even more preferably, the fragmentcomprises at least 340 contiguous nucleotides. Further, the isolated orpurified nucleic acid molecule can hybridize under moderately stringentconditions to an isolated or purified nucleic acid molecule consistingessentially of the nucleotide sequence that is complementary to SEQ IDNO: 1 or a fragment thereof, such as naturally occurring andartificially generated variants. Alternatively, but still preferably,the isolated or purified nucleic acid molecule can share 43% or moreidentity with SEQ ID NO: 1, such as naturally occurring and artificiallygenerated variants. Also preferably, the isolated or purified nucleicacid molecule can share 50% or more identity with SEQ ID NO: 1. Morepreferably, the isolated or purified nucleic acid molecule can share 70%or more identity with SEQ ID NO: 1. Still more preferably, the isolatedor purified nucleic acid molecule can share 90% or more identity withSEQ ID NO: 1.

Alternatively, the isolated or purified nucleic acid molecule can encodethe amino acid sequence of SEQ ID NO: 6 or a fragment thereof comprisingat least 105 contiguous amino acids. More preferably, the fragmentcomprises at least 110 contiguous amino acids. Still more preferably,the fragment comprises at least 115 contiguous amino acids. Even morepreferably, the fragment comprises at least 120 contiguous amino acids.Alternatively, the isolated or purified nucleic acid molecule consistsessentially of the nucleotide sequence of SEQ ID NO: 5 or a fragmentthereof comprising at least 314 contiguous nucleotides. More preferably,the fragment comprises at least 320 contiguous nucleotides. Still morepreferably, the fragment comprises at least 330 contiguous nucleotides.Even more preferably, the fragment comprises at least 340 contiguousnucleotides. Further, the isolated or purified nucleic acid molecule canhybridize under moderately stringent conditions to an isolated orpurified nucleic acid molecule consisting essentially of the nucleotidesequence that is complementary to SEQ ID NO: 5 or a fragment thereof,such as naturally occurring and artificially generated variants.Alternatively, but still preferably, the isolated or purified nucleicacid molecule can share 40% or more identity with SEQ ID NO: 5, such asnaturally occurring and artificially generated variants. Alsopreferably, the isolated or purified nucleic acid molecule can share 45%or more identity with SEQ ID NO: 5. More preferably, the isolated orpurified nucleic acid molecule can share 60% or more identity with SEQID NO: 5. Still more preferably, the isolated or purified nucleic acidmolecule can share 80% or more identity with SEQ ID NO: 5.

Also preferably, the isolated or purified nucleic acid molecule consistsessentially of a nucleotide sequence encoding TDC2 or a fragment thereofcomprising at least 110 contiguous nucleotides. The TDC2 can be a humanTDC2. In a preferred embodiment, the isolated or purified nucleic acidmolecule can encode the amino acid sequence of SEQ ID NO: 4 or afragment thereof comprising at least 70 contiguous amino acids. Morepreferably, the fragment comprises at least 75 contiguous amino acids.Still more preferably, the fragment comprises at least 80 contiguousamino acids. Even more preferably, the fragment comprises at least 85contiguous amino acids. Alternatively, the isolated or purified nucleicacid molecule consists essentially of the nucleotide sequence of SEQ IDNO: 3 or a fragment thereof comprising at least 110 contiguousnucleotides. More preferably, the fragment comprises at least 115contiguous nucleotides. Still more preferably, the fragment comprises atleast 130 contiguous nucleotides. Even more preferably, the fragmentcomprises at least 150 contiguous nucleotides. In a further preferredembodiment, the isolated or purified nucleic acid molecule can hybridizeunder moderately stringent conditions to an isolated or purified nucleicacid molecule consisting essentially of the nucleotide sequence that iscomplementary to SEQ ID NO: 3 or a fragment thereof. Alternatively, butstill preferably, the isolated or purified nucleic acid molecule canshare 49% or more identity with SEQ ID NO: 3. Also preferably, theisolated or purified nucleic acid molecule can share 55% or moreidentity with SEQ ID NO: 3. More preferably, the isolated or purifiednucleic acid molecule can share 70% or more identity with SEQ ID NO: 3.Still more preferably, the isolated or purified nucleic acid moleculecan share 90% or more identity with SEQ ID NO: 3.

Alternatively, but still preferably, the isolated or purified nucleicacid molecule can encode the amino acid sequence of SEQ ID NO:8 or afragment thereof comprising at least 71 contiguous amino acids. Alsopreferably, the isolated or purified nucleic acid molecule can consistessentially of the nucleotide sequence of SEQ ID NO: 7 or a fragmentthereof comprising at least 110 contiguous nucleotides. More preferably,the fragment comprises at least 115 contiguous nucleotides. Still morepreferably, the fragment comprises at least 120 contiguous nucleotides.Even more preferably, the fragment comprises at least 125 nucleotides.In a further preferred embodiment, the fragment can hybridize undermoderately stringent conditions to an isolated or purified nucleic acidmolecule consisting essentially of the nucleotide sequence that iscomplementary to SEQ ID NO: 7 or a fragment thereof. In an alternativeembodiment, the isolated or purified nucleic acid molecule can share 41%or more identity with SEQ ID NO: 7. Alternatively, but still preferably,the isolated or purified nucleic acid molecule can share 55% or moreidentity with SEQ ID NO: 7. More preferably, the isolated or purifiednucleic acid molecule can share 75% or more identity with SEQ ID NO: 7.Still more preferably, the isolated or purified nucleic acid moleculecan share 90% or more identity with SEQ ID NO: 7.

An isolated or purified nucleic acid molecule consisting essentially ofa nucleotide sequence encoding a variant TDC1 or a fragment thereof cancomprise one or more insertions, deletions, inversions and/orsubstitutions. Desirably, the variant TDC1 does not differ functionallyfrom the corresponding unmodified TDC1 or a fragment thereof comprisingat least 314 contiguous nucleotides, such as that comprising SEQ IDNO: 1. Preferably, the one or more substitution(s) results in thesubstitution of an amino acid of the encoded TDC1 with another aminoacid of approximately equivalent mass, structure and charge.

An isolated or purified nucleic acid molecule consisting essentially ofa nucleotide sequence encoding a variant TDC2 or a fragment thereof cancomprise one or more insertions, deletions, inversions and/orsubstitutions. Desirably, the variant TDC2 does not differ functionallyfrom the corresponding unmodified TDC2 or a fragment thereof comprisingat least 110 contiguous nucleotides, such as that comprising SEQ ID NO:3. Preferably, the one or more substitution(s) results in thesubstitution of an amino acid of the encoded TDC2 with another aminoacid of approximately equivalent mass, structure and charge.

The present invention also provides an isolated or purified nucleic acidmolecule consisting essentially of a nucleotide sequence that iscomplementary to a nucleotide sequence encoding human TDC1 or a fragmentthereof. Such an isolated or purified nucleic acid molecule preferablyis complementary to a nucleotide sequence encoding the amino acidsequence of SEQ ID NO: 2 or a fragment thereof comprising at least 105contiguous amino acids. More preferably, the fragment comprises at least110 contiguous amino acids. Still more preferably, the fragmentcomprises at least 115 contiguous amino acids. Even more preferably, thefragment comprises at least 120 contiguous amino acids. Alternatively,but still preferably, the isolated or purified nucleic acid molecule iscomplementary to the nucleotide sequence of SEQ ID NO: 1 or a fragmentthereof comprising at least 314 contiguous nucleotides. In anotherpreferred embodiment, the isolated or purified nucleic acid moleculehybridizes under moderately stringent conditions to an isolated orpurified nucleic acid molecule consisting essentially of SEQ ID NO: 1 ora fragment thereof. Preferably, the isolated or purified nucleic acidmolecule shares 43% or more identity with the nucleotide sequence thatis complementary to SEQ ID NO: 1. More preferably, the isolated orpurified nucleic acid molecule shares 50% or more identity with SEQ IDNO: 1. Even more preferably, the isolated or purified nucleic acidmolecule shares 70% or more sequence identity with SEQ ID NO: 1. Stillmore preferably, the isolated or purified nucleic acid molecule shares90% or more sequence identity with SEQ ID NO: 1. An isolated or purifiednucleic acid molecule consisting essentially of a nucleotide sequencethat is complementary to either of a nucleotide sequence encoding avariant TDC1 or a fragment thereof also can be obtained.

The present invention also provides an isolated or purified nucleic acidmolecule consisting essentially of a nucleotide sequence that iscomplementary to either of a nucleotide sequence encoding human TDC2 ora fragment thereof. Such an isolated or purified nucleic acid moleculepreferably is complementary to a nucleotide sequence encoding the aminoacid sequence of SEQ ID NO: 4 or a fragment thereof comprising at least70 contiguous amino acids. More preferably, the fragment comprises atleast 75 contiguous amino acids. Still more preferably, the fragmentcomprises at least 80 contiguous amino acids. Even more preferably, thefragment comprises at least 85 contiguous amino acids. Alternatively,but still preferably, the isolated or purified nucleic acid molecule iscomplementary to the nucleotide sequence of SEQ ID NO: 3 or a fragmentthereof comprising at least 110 contiguous nucleotides. In anotherpreferred embodiment, the isolated or purified nucleic acid moleculehybridizes under moderately stringent conditions to an isolated orpurified nucleic acid molecule consisting essentially of SEQ ID NO: 3 ora fragment thereof. Preferably, the isolated or purified nucleic acidmolecule shares 49% or more identity with the nucleotide sequence thatis complementary to SEQ ID NO: 3. More preferably, the isolated orpurified nucleic acid molecule shares 55% or more identity with SEQ IDNO: 3. Even more preferably, the isolated or purified nucleic acidmolecule shares 75% or more sequence identity with SEQ ID NO: 3. Stillmore preferably, the isolated or purified nucleic acid molecule shares90% or more sequence identity with SEQ ID NO: 3. An isolated or purifiednucleic acid molecule consisting essentially of a nucleotide sequencethat is complementary to either of a nucleotide sequence encoding avariant TDC2 or a fragment thereof also can be obtained.

Whereas embodiments of the present invention are described in thecontext of applications to humans, the teachings set forth herein can beadapted to other animals as a matter of routine experimentation. Forexample, further disclosed herein are the sequences for a mouse TDC1(SEQ ID NOS: 5 (nucleic acid) and 6 (amino acid)) and a mouse TDC2 (SEQID NOS: 7 (nucleic acid) and 8 (amino acid)). These sequences also canbe used in the context of the present invention and constitutealternative preferred embodiments.

With respect to the above, one of ordinary skill in the art knows how togenerate insertions, deletions, inversions and/or substitutions in agiven nucleic acid molecule. See, for example, the references citedherein under “Example.” It is preferred that the one or moresubstitution(s) result(s) in the substitution of an amino acid withanother amino acid of approximately equivalent mass, structure andcharge.

Also with respect to the above, “does not differ functionally from” isintended to mean that the variant transductin has activitycharacteristic of the unmodified transductin. In other words, itregulates a transductin-responsive gene. However, the varianttransductin can be more or less active than the unmodified transductinas desired in accordance with the present invention.

An indication that polynucleotide sequences are substantially identicalis if two molecules selectively hybridize to each other under moderatelystringent conditions. The phrase “hybridizes to” refers to the selectivebinding of a single-stranded nucleic acid probe to a single-strandedtarget DNA or RNA sequence of complementary sequence when the targetsequence is present in a preparation of heterogeneous DNA and/or RNA.“Moderately stringent conditions” are sequence-dependent and will bedifferent in different circumstances. Generally, moderately stringentconditions are selected to be about 20° C. lower than the thermalmelting point (Tm) for the specific sequence at a defined ionic strengthand pH. The Tm is the temperature (under defined ionic strength and pH)at which 50% of the target sequence hybridizes to a perfectly matchedprobe.

For example, under moderately stringent conditions, as that term isunderstood by one skilled in the art, hybridization is preferablycarried out using a standard hybridization buffer at a temperatureranging from about 50° C. to about 75° C., even more preferably fromabout 60° C. to about 70° C., and optimally from about 65° C. to about68° C. Alternately, formamide can be included in the hybridizationreaction, and the temperature of hybridization can be reduced topreferably from about 35° C. to about 45° C., even more preferably fromabout 40° C. to about 45° C., and optimally to about 42° C. Desirably,formamide is included in the hybridization reaction at a concentrationof from about 30% to about 50%, preferably from about 35% to about 45%,and optimally at about 40%. Moreover, optionally, the hybridizedsequences are washed (if necessary to reduce non-specific binding) underrelatively highly moderately stringent conditions, as that term isunderstood by those skilled in the art. For instance, desirably, thehybridized sequences are washed one or more times using a solutioncomprising salt and detergent, preferably at a temperature of from about50° C. to about 75° C., even more preferably at from about 60° C. toabout 70° C., and optimally from about 65° C. to about 68° C.Preferably, a salt (e.g., such as sodium chloride) is included in thewash solution at a concentration of from about 0.01 M to about 1.0 M.Optimally, a detergent (e.g., such as sodium dodecyl sulfate) is alsoincluded at a concentration of from about 0.01% to about 1.0%.

The following are examples of highly stringent and moderately stringentconditions for a Southern hybridization in aqueous buffers (noformamide) (Sambrook and Russell, Molecular Cloning, 3rd Ed. SCHL Press(2001)):

Highly stringent Moderately Stringent hybridization conditions:hybridization conditions: 6X SSC or 6X SSPE 6X SSC or 6X SSPE 5xDenhardt's Reagent 5x Denhardt's Reagent 1% SDS 1% SDS 100 μg/ml salmonsperm DNA 10 μg/ml salmon sperm DNA hybridization at 65–68° C.hybridization at 58–64° C. Highly stringent Moderately stringent washingconditions: washing conditions: 0.1X SSC/0.1% SDS 2X SSC/0.1% SDSwashing at 65–68° C. washing at 58–64° C.

In view of the above, “stringent conditions” preferably allow for about20% mismatch, more preferably up to about 15% mismatch, and mostpreferably up to about 5% mismatch, such as 4%, 3%, 2%, or 1% mismatch.“At least moderately stringent conditions” preferably allow for up toabout 40% mismatch, more preferably up to about 30% mismatch, and mostpreferably up to about 20% mismatch. “Low stringency conditions”preferably allow for up to about 60% mismatch, more preferably up toabout 50% mismatch, and most preferably up to about 40% mismatch. Withrespect to the preceding ranges of mismatch, 1% mismatch corresponds toone degree decrease in the melting temperature.

The above isolated or purified nucleic acid molecules also can becharacterized in terms of “percentage of sequence identity.” In thisregard, a given nucleic acid molecule as described above can be comparedto a nucleic acid molecule encoding a corresponding gene (i.e., thereference sequence) by optimally aligning the nucleic acid sequencesover a comparison window, wherein the portion of the polynucleotidesequence in the comparison window may comprise additions or deletions(i.e., gaps) as compared to the reference sequence, which does notcomprise additions or deletions, for optimal alignment of the twosequences. The percentage of sequence identity is calculated bydetermining the number of positions at which the identical nucleic acidbase occurs in both sequences, i.e., the number of matched positions,dividing the number of matched positions by the total number ofpositions in the window of comparison, and multiplying the result by 100to yield the percentage of sequence identity. Optimal alignment ofsequences for comparison may be conducted by computerizedimplementations of known algorithms (e.g., GAP, BESTFIT, FASTA, andTFASTA in the Wisconsin Genetics Software Package, Genetics ComputerGroup (GCG), 575 Science Dr., Madison, Wis., or BlastN and BlastXavailable from the National Center for Biotechnology Information,Bethesda, Md.), or by inspection. Sequences are typically compared usingBESTFIT or BlastN with default parameters.

“Substantial sequence identity” means that at least 75%, preferably atleast 80%, more preferably at least 90%, and most preferably at least95% (such as 96%, 97%, 98% or 99%) of the sequence of a given nucleicacid molecule is identical to a given reference sequence. Typically, twopolypeptides are considered to be substantially similar if at least 40%,preferably at least 60%, more preferably at least 90%, and mostpreferably at least 95% (such as 96%, 97%, 98% or 99%) of the aminoacids of which the polypeptides are comprised are identical to orrepresent conservative substitutions of the amino acids of a givenreference sequence.

One of ordinary skill in the art will appreciate, however, that twopolynucleotide sequences can be substantially different at the nucleicacid level, yet encode substantially similar, if not identical, aminoacid sequences, due to the degeneracy of the genetic code. The presentinvention is intended to encompass such polynucleotide sequences.

While the above-described nucleic acid molecules can be isolated orpurified, alternatively they can be synthesized. Methods of nucleic acidsynthesis are known in the art. See, e.g., the references cited hereinunder “Examples.”

The above-described nucleic acid molecules can be used, in whole or inpart (i.e., as fragments or primers), to identify and isolatecorresponding genes from other organisms for use in the context of thepresent inventive method using conventional means known in the art. See,for example, the references cited herein under “Examples.”

In view of the above, the present invention also provides a vectorcomprising an above-described isolated or purified nucleic acidmolecule. A nucleic acid molecule as described above can be cloned intoany suitable vector and can be used to transform or transfect anysuitable host. The selection of vectors and methods to construct themare commonly known to persons of ordinary skill in the art and aredescribed in general technical references (see, in general, “RecombinantDNA Part D,” Methods in Enzymology, Vol. 153, Wu and Grossman, eds.,Academic Press (1987) and the references cited herein under “Examples”).Desirably, the vector comprises regulatory sequences, such astranscription and translation initiation and termination codons, whichare specific to the type of host (e.g., bacterium, fungus, plant oranimal) into which the vector is to be introduced, as appropriate andtaking into consideration whether the vector is DNA or RNA. Preferably,the vector comprises regulatory sequences that are specific to the genusof the host. Most preferably, the vector comprises regulatory sequencesthat are specific to the species of the host.

Constructs of vectors, which are circular or linear, can be prepared tocontain an entire nucleic acid sequence as described above or a portionthereof ligated to a replication system functional in a prokaryotic oreukaryotic host cell. Replication systems can be derived from ColE1, 2mμ plasmid, λ, SV40, bovine papillomavirus, and the like.

In addition to the replication system and the inserted nucleic acid, theconstruct can include one or more marker genes, which allow forselection of transformed or transfected hosts. Marker genes includebiocide resistance, e.g., resistance to antibiotics, heavy metals, etc.,complementation in an auxotrophic host to provide prototrophy, and thelike.

Suitable vectors include those designed for propagation and expansion orfor expression or both. A preferred cloning vector is selected from thegroup consisting of the pUC series the pBluescript series (Stratagene,LaJolla, Calif.), the pET series (Novagen, Madison, Wis.), the pGEXseries (Pharmacia Biotech, Uppsala, Sweden), and the pEX series(Clonetech, Palo Alto, Calif.). Bacteriophage vectors, such as λGT10,λGT11, λZapII (Stratagene), λ EMBL4, and λ NM1149, also can be used.Examples of plant expression vectors include pBI101, pBI101.2, pBI101.3,pBI121 and pBIN19 (Clonetech, Palo Alto, Calif.). Examples of animalexpression vectors include pEUK-C1, pMAM and pMAMneo (Clonetech).

An expression vector can comprise a native or normative promoteroperably linked to an isolated or purified nucleic acid molecule asdescribed above. The selection of promoters, e.g., strong, weak,inducible, tissue-specific and developmental-specific, is within theskill in the art. Similarly, the combining of a nucleic acid molecule asdescribed above with a promoter is also within the skill in the art.

Also in view of the above, the present invention provides a cellcomprising an isolated or purified nucleic acid molecule or a vector asdescribed above. Examples of suitable cells include, but are not limitedto, a human cell, a human cell line, E. coli, (e.g., E. coli TB-1, TG-2,DH5α, XL-Blue MRF′ (Stratagene), SA2821 and Y1090) B. subtilis, P.aerugenosa, S. cerevisiae, and N. crassa.

The present invention further provides an isolated or purifiedpolypeptide molecule consisting essentially of an amino acid sequenceencoding TDC1 or a fragment thereof comprising at least 95 contiguousamino acids, either one of which is optionally glycosylated, amidated,carboxylated, phosphorylated, esterified, N-acylated or converted intoan acid addition salt. The isolated or purified polypeptide molecule ispreferably obtained from a mammalian source. Even more preferably, themammalian source is a human. The isolated or purified polypeptidemolecule can be encoded by the nucleotide sequence of SEQ ID NO:1 or afragment thereof comprising at least 285 contiguous nucleotides.Preferably, the isolated or purified polypeptide molecule consistsessentially of the amino acid sequence of SEQ ID NO: 2 or a fragmentthereof comprising at least 95 contiguous amino acids. More preferably,the fragment comprises at least 100 contiguous amino acids. Still morepreferably, the fragment comprises at least 105 contiguous amino acids.Even more preferably, the fragment comprises at least 110 contiguousamino acids. Alternatively, but still preferably, the isolated orpurified polypeptide molecule shares 24% or more identity with SEQ IDNO: 2. More preferably, the isolated or purified polypeptide moleculeshares 30% or more identity with SEQ ID NO: 2. Still more preferably,the isolated or purified polypeptide molecule shares 45% or moreidentity with SEQ ID NO: 2. Even more preferably, the isolated orpurified polypeptide molecule shares 65% or more identity with SEQ IDNO: 2.

In a further embodiment, the isolated or purified polypeptide moleculecan be encoded by the nucleotide sequence of SEQ ID NO: 5 or a fragmentthereof comprising at least 285 contiguous nucleotides. Additionally,the isolated or purified polypeptide molecule can consist essentially ofthe amino acid sequence of SEQ ID NO: 6 or a fragment thereof comprisingat least 95 contiguous amino acids. More preferably, the fragmentcomprises at least 100 contiguous amino acids. Still more preferably,the fragment comprises at least 115 contiguous amino acids. Even morepreferably, the fragment comprises at least 130 contiguous amino acids.Alternatively, the isolated or purified polypeptide molecule shares 25%or more identity with SEQ ID NO: 6. More preferably, the isolated orpurified polypeptide molecule shares 30% or more identity with SEQ IDNO: 6. Still more preferably, the isolated or purified polypeptidemolecule shares 45% or more identity with SEQ ID NO: 6. Even morepreferably, the isolated or purified polypeptide molecule shares 65% ormore identity with SEQ ID NO: 6.

An isolated or purified polypeptide molecule consisting essentially ofan amino acid sequence encoding a variant TDC1 or a fragment thereof cancomprise at least 95 contiguous amino acids, which is optionallyglycosylated, amidated, carboxylated, phosphorylated, esterified,N-acylated or converted into an acid addition salt. Still preferably,the fragment comprises at least 100 contiguous amino acids. Still morepreferably, the fragment comprises at least 105 contiguous amino acids.Even more preferably, the fragment comprises at least 110 contiguousamino acids.

The present invention further provides an isolated or purifiedpolypeptide molecule consisting essentially of an amino acid sequenceencoding TDC2 or a fragment thereof comprising at least 71 contiguousamino acids, either one of which is optionally glycosylated, amidated,carboxylated, phosphorylated, esterified, N-acylated or converted intoan acid addition salt. The isolated or purified polypeptide molecule ispreferably obtained from a mammalian source. Even more preferably, themammalian source is a human. The isolated or purified polypeptidemolecule can be encoded by the nucleotide sequence of SEQ ID NO: 3 or afragment thereof comprising at least 213 contiguous nucleotides.Preferably, the isolated or purified polypeptide molecule consistsessentially of the amino acid sequence of SEQ ID NO: 4 or a fragmentthereof comprising at least 71 contiguous amino acids. More preferably,the fragment comprises at least 75 contiguous amino acids. Still morepreferably, the fragment comprises at least 90 contiguous amino acids.Even more preferably, the fragment comprises at least 105 contiguousamino acids. Alternatively, but still preferably, the isolated orpurified polypeptide molecule shares 31% or more identity with SEQ IDNO: 4. More preferably, the isolated or purified polypeptide moleculeshares 40% or more identity with SEQ ID NO: 4. Still more preferably,the isolated or purified polypeptide molecule shares 55% or moreidentity with SEQ ID NO: 4. Even more preferably, the isolated orpurified polypeptide molecule shares 75% or more identity with SEQ IDNO: 4.

In a further embodiment, the isolated or purified polypeptide moleculecan be encoded by the nucleotide sequence of SEQ ID NO: 7 or a fragmentthereof comprising at least 213 contiguous nucleotides. Preferably, theisolated or purified polypeptide molecule consists essentially of theamino acid sequence of SEQ ID NO: 8 or a fragment thereof comprising atleast 71 contiguous amino acids. More preferably, the fragment comprisesat least 75 contiguous amino acids. Still more preferably, the fragmentcomprises at least 90 contiguous amino acids. Even more preferably, thefragment comprises at least 105 contiguous amino acids. Alternatively,but still preferably, the isolated or purified polypeptide moleculeshares 34% or more identity with SEQ ID NO: 8. More preferably, theisolated or purified polypeptide molecule shares 40% or more identitywith SEQ ID NO: 8. Still more preferably, the isolated or purifiedpolypeptide molecule shares 55% or more identity with SEQ ID NO: 8. Evenmore preferably, the isolated or purified polypeptide molecule shares75% or more identity with SEQ ID NO: 8.

An isolated or purified polypeptide molecule consisting essentially ofan amino acid sequence encoding a variant TDC2 or a fragment thereof cancomprise at least 71 contiguous amino acids, which is optionallyglycosylated, amidated, carboxylated, phosphorylated, esterified,N-acylated or converted into an acid addition salt. Still preferably,the fragment comprises at least 75 contiguous amino acids. Still morepreferably, the fragment comprises at least 90 contiguous amino acids.Even more preferably, the fragment comprises at least 115 contiguousamino acids.

The polypeptide preferably comprises an amino end and a carboxyl end.The polypeptide can comprise D-amino acids, L-amino acids or a mixtureof D- and L-amino acids. The D-form of the amino acids, however, isparticularly preferred since a polypeptide comprised of D-amino acids isexpected to have a greater retention of its biological activity in vivo,given that the D-amino acids are not recognized by naturally occurringproteases.

The polypeptide can be prepared by any of a number of conventionaltechniques. The polypeptide can be isolated or purified from a naturallyoccurring source or from a recombinant source. For instance, in the caseof recombinant polypeptides, a DNA fragment encoding a desired peptidecan be subcloned into an appropriate vector using well-known moleculargenetic techniques (see, e.g., Maniatis et al., Molecular Cloning: ALaboratory Manual, 2nd ed. (Cold Spring Harbor Laboratory, 1989); andSambrook et al., Molecular Cloning: A Laboratory Manual, 2nd ed. ColdSpring Harbor Press, Cold Spring Harbor, N.Y., 1989). The fragment canbe transcribed and the polypeptide subsequently translated in vitro.Commercially available kits can also be employed (e.g., such asmanufactured by Clontech, Palo Alto, Calif.; Amersham Life Sciences,Inc., Arlington Heights, Ill.; In Vitrogen, San Diego, Calif., and thelike). The polymerase chain reaction optionally can be employed in themanipulation of nucleic acids. In addition, the polypeptide or fragmentthereof can be glycosylated in accordance with methods known in the art.

Alterations of the native amino acid sequence to produce variantpolypeptides can be done by a variety of means known to those skilled inthe art. For instance, site-specific mutations can be introduced byligating into an expression vector a synthesized oligonucleotidecomprising the modified site. Alternately, oligonucleotide-directedsite-specific mutagenesis procedures can be used such as disclosed inWalder et al., Gene, 42, 133 (1986); Bauer et al., Gene, 37, 73 (1985);Craik, Biotechniques, 12–19 (January 1995); and U.S. Pat. Nos. 4,518,584and 4,737,462.

With respect to the above isolated or purified polypeptides, one ofordinary skill in the art will appreciate that insertions, deletions,inversions and/or substitutions in a nucleotide sequence coding forfunctional domains of the transductin molecule can lead to anon-functional transductin molecule. Preferably, any variants, asdescribed above, would contain mutations such as insertions, deletions,inversions and/or substitutions in domains which are not critical fortransductin activity. For example, as an integral membrane protein, aninsertion, inversion, deletion and/or substitution to the transmembranedomain of the transductin molecule may render the molecule unable toinsert into the membrane, thus rendering it ineffective as a channelthrough the cell membrane. Alternatively, the mutation as describedabove may affect the ability of the channel pore domain to movemolecules across the cell membrane. Other domains which are critical fortransductin activity can be identified by determining if a mutation(s)to those domains causes a decrease in transductin activity.

Any appropriate expression vector (e.g., as described in Pouwels et al.,Cloning Vectors: A Laboratory Manual (Elsevior, N.Y.: 1985)) andcorresponding suitable host can be employed for production ofrecombinant polypeptides. Expression hosts include, but are not limitedto, bacterial species within the genera Escherichia, Bacillus,Pseudomonas, Salmonella, mammalian or insect host cell systems includingbaculovirus systems (e.g., as described by Luckow et al.,Bio/Technology, 6, 47 (1988)), and established cell lines such as theCOS-7, C127, 3T3, CHO, HeLa, BHK cell line, and the like. The ordinaryskilled artisan is, of course, aware that the choice of expression hosthas ramifications for the type of polypeptide produced. For instance theglycosylation of polypeptides produced in yeast or mammalian cells(e.g., COS-7 cells) will differ from that of polypeptides produced inbacterial cells such as Escherichia coli.

Alternately, the polypeptide (including the variant peptides) can besynthesized using standard peptide synthesizing techniques well-known tothose of skill in the art (e.g., as summarized in Bodanszky, Principlesof Peptide Synthesis, (Springer-Verlag, Heidelberg: 1984)). Inparticular, the polypeptide can be synthesized using the procedure ofsolid-phase synthesis (see, e.g., Merrifield, J. Am. Chem. Soc. 85,2149–54 (1963); Barany et al., Int. J. Peptide Protein Res., 30, 705–739(1987); and U.S. Pat. No. 5,424,398). If desired, this can be done usingan automated peptide synthesizer. Removal of the t-butyloxycarbonyl(t-BOC) or 9-fluorenylmethyloxycarbonyl (Fmoc) amino acid blockinggroups and separation of the polypeptide from the resin can beaccomplished by, for example, acid treatment at reduced temperature. Thepolypeptide-containing mixture can then be extracted, for instance, withdimethyl ether, to remove non-peptidic organic compounds, and thesynthesized polypeptide can be extracted from the resin powder (e.g.,with about 25% w/v acetic acid). Following the synthesis of thepolypeptide, further purification (e.g., using high performance liquidchromatography (HPLC)) optionally can be done in order to eliminate anyincomplete polypeptides or free amino acids. Amino acid and/or HPLCanalysis can be performed on the synthesized polypeptide to validate itsidentity. For other applications according to the invention, it may bepreferable to produce the polypeptide as part of a larger fusionprotein, either by chemical conjugation, or through genetic means, suchas are known to those skilled in the art.

If desired, the polypeptides of the invention (including variantpolypeptides) can be modified, for instance, by glycosylation,amidation, carboxylation, or phosphorylation, or by the creation of acidaddition salts, amides, esters, in particular C-terminal esters, andN-acyl derivatives of the polypeptides of the invention. Thepolypeptides also can be modified to create polypeptide derivatives byforming covalent or noncovalent complexes with other moieties inaccordance with methods known in the art. Covalently-bound complexes canbe prepared by linking the chemical moieties to functional groups on theside chains of amino acids comprising the polypeptides, or at the N- orC-terminus.

Thus, in this regard, the present invention also provides a conjugatecomprising an above-described isolated or purified polypeptide moleculeor fragment thereof and a targeting moiety. Preferably, the targetingmoiety is an antibody or an antigenically reactive fragment thereof.Alternatively, the targeting moiety can be a reporter group, including,but not limited to a radiolabel, a fluorescent label, an enzyme (e.g.,that catalyzes a calorimetric or fluorometric reaction), a substrate, asolid matrix, or a carrier (e.g., biotin or avidin). Methods ofconjugation are known in the art. In addition, conjugate kits arecommercially available.

The present invention also provides a composition comprising apharmaceutically acceptable carrier and either (i) an above-describedisolated or purified nucleic acid molecule or fragment thereof, (ii) anabove-described vector, (iii) an above-described polypeptide molecule orfragment thereof, or (iv) an above-described conjugate comprising anabove-described isolated or purified polypeptide molecule or fragmentthereof and a targeting moiety. Pharmaceutically acceptable carriers arewell-known in the art, and are readily available. The choice of carrierwill be determined in part by the particular route of administration andwhether a nucleic acid molecule or a polypeptide molecule (or conjugatethereof) is being administered. Accordingly, there is a wide variety ofsuitable formulations for use in the context of the present invention,and the invention expressly provide a pharmaceutical composition thatcomprises an active agent of the invention and a pharmaceuticallyacceptable carrier therefor. The following methods and carriers aremerely exemplary and are in no way limiting.

Formulations suitable for oral administration can consist of (a) liquidsolutions, such as an effective amount of the compound dissolved indiluent, such as water, saline, or orange juice; (b) capsules, sachetsor tablets, each containing a predetermined amount of the activeingredient, as solids or granules; (c) suspensions in an appropriateliquid; and (d) suitable emulsions. Tablet forms can include one or moreof lactose, mannitol, corn starch, potato starch, microcrystallinecellulose, acacia, gelatin, colloidal silicon dioxide, croscarmellosesodium, talc, magnesium stearate, stearic acid, and other excipients,colorants, diluents, buffering agents, moistening agents, preservatives,flavoring agents, and pharmacologically compatible excipients. Lozengeforms can comprise the active ingredient in a flavor, usually sucroseand acacia or tragacanth. Pastilles can comprise the active ingredientin an inert base, such as gelatin and glycerin, or sucrose and acacia,emulsions, gels, and the like containing, in addition to the activeingredient, such excipients/carriers as are known in the art.

An active agent of the present invention, either alone or in combinationwith other suitable components, can be made into aerosol formulations tobe administered via inhalation. These aerosol formulations can be placedinto pressurized acceptable propellants, such asdichlorodifluoromethane, propane, nitrogen, and the like. They also canbe formulated as pharmaceuticals for non-pressured preparations such asin a nebulizer or an atomizer.

Formulations suitable for parenteral administration include aqueous andnon-aqueous, isotonic sterile injection solutions, which can containanti-oxidants, buffers, bacteriostats, and solutes that render theformulation isotonic with the blood of the intended recipient, andaqueous and non-aqueous sterile suspensions that can include suspendingagents, solubilizers, thickening agents, stabilizers, and preservatives.The formulations can be presented in unit-dose or multi-dose sealedcontainers, such as ampules and vials, and can be stored in afreeze-dried (lyophilized) condition requiring only the addition of thesterile liquid excipient, for example, water, for injections,immediately prior to use. Extemporaneous injection solutions andsuspensions can be prepared from sterile powders, granules, and tabletsof the kind previously described.

Additionally, active agents of the present invention can be made intosuppositories by mixing with a variety of bases such as emulsifyingbases or water-soluble bases. Formulations suitable for vaginaladministration can be presented as pessaries, tampons, creams, gels,pastes, foams, or spray formulas containing, in addition to the activeingredient, such carriers as are known in the art to be appropriate.Further suitable formulations are found in Remington's PharmaceuticalSciences, 17th ed., (Mack Publishing Company, Philadelphia, Pa.: 1985),and methods of drug delivery are reviewed in, for example, Langer,Science, 249, 1527–1533 (1990).

A targeting moiety also can be used in the contact of a cell with anabove-described isolated or purified nucleic acid molecule. In thisregard, any molecule that can be linked with the therapeutic nucleicacid directly or indirectly, such as through a suitable deliveryvehicle, such that the targeting moiety binds to a cell-surfacereceptor, can be used. The targeting moiety can bind to a cell through areceptor, a substrate, an antigenic determinant or another binding siteon the surface of the cell. Examples of a targeting moiety include anantibody (i.e., a polyclonal or a monoclonal antibody), animmunologically reactive fragment of an antibody, an engineeredimmunoprotein and the like, a protein (target is receptor, as substrate,or regulatory site on DNA or RNA), a polypeptide (target is receptor), apeptide (target is receptor), a nucleic acid, which is DNA or RNA (i.e.,single-stranded or double-stranded, synthetic or isolated and purifiedfrom nature; target is complementary nucleic acid), a steroid (target issteroid receptor), and the like.

Analogs of targeting moieties that retain the ability to bind to adefined target also can be used. In addition, synthetic targetingmoieties can be designed, such as to fit a particular epitope.Alternatively, the therapeutic nucleic acid can be encapsulated in aliposome comprising on its surface the targeting moiety.

The targeting moiety includes any linking group that can be used to joina targeting moiety to, in the context of the present invention, anabove-described nucleic acid molecule. It will be evident to one skilledin the art that a variety of linking groups, including bifunctionalreagents, can be used. The targeting moiety can be linked to thetherapeutic nucleic acid by covalent or non-covalent bonding. If bondingis non-covalent, the conjugation can be through hydrogen bonding, ionicbonding, hydrophobic or van der Waals interactions, or any otherappropriate type of binding.

Further provided by the present invention is a cell line that produces amonoclonal antibody that is specific for an above-described isolated orpurified polypeptide molecule. Methods of making such cell lines areknown in the art (see, e.g., the references cited herein under“Examples.”). Preferably, the cells from which the cell line is createdare pluripotent stem cells. Even more preferably, the cells aretotipotent stem cells. Thus, the present invention also provides themonoclonal antibody produced by the cell line.

The invention further provides methods for detecting hearing loss or apredisposition to hearing loss in an animal. In one embodiment, themethod comprises detecting at least one mutation such as 1714G→A(D572N), 100C→T (R34X), 1534C→T (R512X), 295 del A (frameshift andpremature termination), 1960 A→G (M654V), IVS3_IVS5del27 kb, IVS13+1G→A,or IVS10-8T→A, in a gene encoding TDC1 in a test sample comprising anucleic acid comprising the TDC1 gene, and/or a polymorphism thereof,obtained from the animal, wherein the at least one mutation isindicative of hearing loss or a predisposition to hearing loss in theanimal. In another embodiment, the method comprises detecting at leastone mutation in a gene encoding TDC2 in a test sample comprising anucleic acid comprising the TDC2 gene, and/or a polymorphism thereof,obtained from the animal, wherein the at least one mutation isindicative of hearing loss or a predisposition to hearing loss in theanimal. The hearing loss can be hereditary, and can further besensorineural hearing loss. The method can further be used to treatnonsyndromic autosomal-dominant hearing loss. The hearing loss can alsobe aminoglycoside induced. Furthermore, the hearing loss can be linkedto DFNA 36. The method also has application wherein the at least onemutation compromises the ability of the TDC1/TDC2 gene product to form acomponent of a hair cell of the inner ear of the animal. The componentof the hair cell can be all or some of an ion transduction channel ofthe hair cell of the inner ear of the animal. Alternatively, the atleast one mutation can compromise the mechanosensory activity of theTDC1/TDC2 gene product.

The at least one mutation (e.g., at least two mutations, at least threemutations, at least four mutations, at least five mutations, or even atleast ten mutations) in a gene encoding transductin is defined herein asany one or more mutations in the gene encoding transductin which is/areindicative of hearing loss or a predisposition to hearing loss in ananimal. The at least one mutation can be, for example, any frame-shiftmutations, missense mutations and/or nonsense mutations, arising fromany insertion, duplication, deletion, inversion, and/or substitution ina gene encoding transductin. The at least one mutation can causetranscriptional, post-transcriptional, translational, and/orpost-translational processing errors, e.g., a translation error whereintranslation begins at a codon encoding a methionine other than the firstmethionine of the transductin gene (e.g., a codon encoding the thirdmethionine of the transductin gene). Moreover, the at least one mutationin the transductin gene can cause one or more splicing errors (i.e.,splicing mutations), such that a mutant transductin gene is produced.Alternatively, or in addition to, the at least one mutation in thetransductin gene can be a mutation that causes transcriptional,post-transcriptional, translational, and/or post-translationalprocessing of the transductin gene to stop prematurely, thereby leadingto the expression of a truncated form of transductin. The at least onemutation can also cause a decreased efficiency of transcriptional,post-transcriptional, translational, and/or post-translationalprocessing of the transductin gene product. Moreover, the at least onemutation in the transductin gene can be associated with a compromisedability of the transductin gene product to function normally, ascompared to wild-type transductin.

The at least one mutation in the transductin gene can be detected at oneor more nucleic acid positions of the transductin gene, e.g., within anycoding region, and/or regulatory region of the transductin gene. The atleast one mutation in the transductin gene is indicative of hearing lossor a predisposition to hearing loss in the animal if, for example, theat least one mutation compromises the transmembrane domain allowing thetransductin molecule to traverse the cell membrane. The at least onemutation in the transductin gene also is indicative of hearing loss or apredisposition to hearing loss in an animal if it compromises theability of the transductin molecule from associating with other suchmolecules to form an ion channel. Moreover, the at least one mutation inthe transductin gene is indicative of hearing loss or a predispositionto hearing loss in an animal if the at least one mutation compromisesthe ability of the transductin gene product to become activated, ascompared to wild-type transductin; or compromises the ability of thechannel complex to channel ions across a cell membrane.

The transductin gene in a test sample obtained from an animal can beamplified using any suitable amplification method known in the art,e.g., polymerase chain reaction (PCR); reverse transcriptase PCR(RT-PCR); ligase chain reaction (LCR) (disclosed in U.S. Pat. No.4,883,750); isothermal amplification (disclosed in Walker et al., Proc.Natl. Acad. Sci. USA 89: 392–396 (1992)); strand displacementamplification (SDA); and repair chain reaction (RCR). Target-specificsequences also can be detected using a cyclic probe reaction (CPR).Moreover, alternative methods for reverse transcription are described inWO 90/07641.

Any primer sequences can be used in the amplification process, as longas the primer sequences are hybridizable to nucleic acids encoding awild-type transductin gene, a mutant transductin gene, and/or functionalsequence analogs thereof. For example, M13-tailed primers can be used inthe amplification process (see Table 1).

The nucleic acid used as a template for amplification can be isolatedfrom a test sample using any standard methodology (Sambrook et al.,Molecular Cloning: A Laboratory Manual, 2^(nd) Ed., Cold Spring HarborPress, Cold Spring Harbor, N.Y., 1989). Alternatively, or in additionto, chromatographic techniques can be employed to effect separation. Itwill be understood that there are many kinds of chromatography which canbe used in the context of the method, e.g., adsorption, partition,ion-exchange and molecular sieve, and many specialized techniques forusing them including column, paper, thin-layer and gas chromatography(Freifelder, Physical Biochemistry Applications to Biochemistry andMolecular Biology, 2^(nd) Ed., Wm. Freeman and Co., New York, N.Y.(1982)).

Amplification products must be visualized in order to confirmamplification of the transductin gene. One typical visualization methodinvolves staining of a gel with ethidium bromide and visualization underUV light. Alternatively, if the amplification products are integrallylabeled with radio- or fluorometrically-labeled nucleotides, theamplification products can then be exposed to x-ray film or visualizedunder the appropriate stimulating spectra, following separation. In oneembodiment, visualization is achieved indirectly. Following separationof amplification products, a labeled, nucleic acid probe is brought intocontact with and allowed to hybridize with the amplified transductingene sequence. The probe preferably is conjugated to a chromophore, butmay be radiolabeled. In another embodiment, the probe is conjugated to abinding partner, such as an antibody or biotin, where the other memberof the binding pair carries a detectable moiety (i.e., a label). Oneexample of the foregoing is described in U.S. Pat. No. 5,279,721, whichdiscloses an apparatus and method for the automated electrophoresis andtransfer of nucleic acids.

When hybridization is employed, preferably, the hybridization is doneunder high stringency conditions. By “high stringency conditions” ismeant that the probe specifically hybridizes to a target sequence in anamount that is detectably stronger than non-specific hybridization. Highstringency conditions, then, are conditions that distinguish apolynucleotide with an exact complementary sequence, or one containingonly a few scattered mismatches from a random sequence that happened tohave a few small regions (e.g., 3–10 bases) that matched the probe. Suchsmall regions of complementarity are more easily melted than afull-length complement of 14–17 or more bases, and moderate stringencyhybridization makes them easily distinguishable. Relatively highstringency conditions include, for example, low salt and/or hightemperature conditions, such as provided by about 0.02–0.1 M NaCl or theequivalent, at temperatures of about 50–70° C. Such relatively highstringency conditions tolerate little, if any, mismatch between theprobe and the template or target strand, and are particularly suitablefor detecting expression of specific transductins. It is generallyappreciated that conditions can be rendered more stringent by theaddition of increasing amounts of formamide.

The at least one mutation can be detected by sequencing the transductingene, and comparing the sequence to the wild-type sequence.Alternatively, the at least one mutation may be detected by Southernblot hybridization, a method well known in the art. Yet anotheralternative is by allele-specific PCR amplification of genomic DNA.

In addition to the above, the invention provides a method of determiningthe level of nucleic acid comprising the wild-type TDC1 gene and/or amutant TDC1 gene in a test sample comprising a nucleic acid comprisingthe wild-type TDC1 gene and/or a mutant TDC1 gene obtained from ananimal. The method comprises assaying the test sample for the level ofnucleic acid comprising the wild-type TDC1 gene and/or a mutant TDC1gene, wherein a decrease in the level of nucleic acid comprising thewild-type TDC1 gene and/or an increase in the level of nucleic acidcomprising a mutant TDC1 gene in the test sample as compared to acontrol sample is indicative of hearing loss (e.g., hearing loss) or apredisposition to hearing loss in the animal.

In addition to the above, the invention provides a method of determiningthe level of nucleic acid comprising the wild-type TDC2 gene and/or amutant TDC2 gene in a test sample comprising a nucleic acid comprisingthe wild-type TDC2 gene and/or a mutant TDC2 gene obtained from ananimal. The method comprises assaying the test sample for the level ofnucleic acid comprising the wild-type TDC2 gene and/or a mutant TDC2gene, wherein a decrease in the level of nucleic acid comprising thewild-type TDC2 gene and/or an increase in the level of nucleic acidcomprising a mutant TDC2 gene in the test sample as compared to acontrol sample is indicative of hearing loss (e.g., hearing loss) or apredisposition to hearing loss in the animal.

A wild-type transductin gene is defined herein is any transductin genethat encodes an transductin gene product that has (i.e., possesses)cation channel capabilities across a cell membrane. A mutant transductingene is defined herein as any transductin gene that encodes atransductin gene product which has a compromised ability (e.g., littleor no ability) to channel cations across a cell membrane, as compared towild-type transductin.

The level of a wild-type transductin gene and/or a mutant transductingene in a test sample obtained from an animal is defined herein as thequantity of nucleic acid comprising a wild-type transductin gene and/orthe quantity of nucleic acid comprising a mutant transductin gene in thetest sample. “Decreased” and “increased” levels of the wild-typetransductin gene and/or a mutant transductin gene are determined by acomparison of the level of wild-type and/or mutant transductin genespresent in a test sample obtained from an animal to any suitable controltest sample. Suitable control test samples include, for example, a testsample obtained from the same animal at a different point in time and atest sample obtained from a different animal of the same species.

Various assays can be used to measure the presence and/or level ofnucleic acid (i.e., DNA or RNA) comprising a wild-type transductin geneand/or a mutant transductin gene present in a test sample obtained froman animal. For example, assays including PCR and microarray analysis canbe used to detect the presence and/or absence of the wild-typetransductin gene and/or a mutant transductin gene, as described, forexample, in U.S. Pat. Nos. 6,197,506 and 6,040,138. Moreover, it isunderstood that the type of assay used depends on whether the nucleicacid of interest being assayed is DNA or RNA. Assays for determining thelevel of DNA comprising a wild-type transductin gene and/or a mutanttransductin gene in a test sample include, for example, Southernhybridization (i.e., a Southern blot), in situ hybridization andmicroarray analysis. Assays for determining the level of RNA (e.g.,mRNA) comprising a wild-type transductin gene and/or a mutanttransductin gene in a test sample include, for example, Northernhybridization (i.e., a Northern blot), in situ hybridization andmicroarray analysis.

It is also understood that a nucleic acid sequence that specificallybinds to, or associates with, a nucleic acid comprising a gene encodingtransductin, whether DNA or RNA, can be attached to a label fordetermining hybridization. A wide variety of appropriate labels areknown in the art, including, for example, fluorescent, radioactive, andenzymatic labels, as well as ligands (e.g., avidin/biotin), which arecapable of being detected. Preferably, a fluorescent label or an enzymetag, such as urease, alkaline phosphatase or peroxidase, is used insteadof a radioactive or other environmentally undesirable label. In the caseof enzyme tags, colorimetric indicator substrates are known which can beemployed to provide a detection system that is visiblespectrophotometrically, or even visible to the human eye to identifyspecific hybridization with complementary transductin nucleicacid-containing samples.

The invention also provides for the use of the method in prognosticatinghearing loss (e.g., hearing loss) in an animal. The method comprisesdetermining the level of nucleic acid comprising the wild-type TDC1/TDC2gene and/or a mutant TDC1/TDC2 gene in a test sample comprising anucleic acid comprising the wild-type TDC1/TDC2 gene and/or a mutantTDC1/TDC2 gene obtained from the animal, and comparing the level ofnucleic acid comprising the wild-type TDC1/TDC2 gene and/or a mutantTDC1/TDC2 gene in the test sample to the level of nucleic acidcomprising the wild-type TDC1/TDC2 gene and/or a mutant TDC1/TDC2 gene,respectively, in another test sample obtained from the animal over time,wherein a decrease in the level of nucleic acid comprising the wild-typeTDC1/TDC2 gene and/or an increase in the level of nucleic acidcomprising a mutant TDC1/TDC2 gene is indicative of an unfavorableprognosis, an increase in the level of the nucleic acid comprising thewild-type TDC1/TDC2 gene and/or a decrease in the level of the nucleicacid comprising a mutant TDC1/TDC2 gene is indicative of a favorableprognosis, and no change in the level of nucleic acid comprising thewild-type TDC1/TDC2 gene and/or a mutant TDC1/TDC2 gene is indicative ofno change in the hearing loss.

The invention also provides for the use of the method in assessing theefficacy of treatment of hearing loss in the animal with a givenanti-hearing loss agent. The method comprises comparing the level ofnucleic acid comprising the wild-type TDC1/TDC2 gene and/or a mutantTDC1/TDC2 gene in the test sample to the level of nucleic acidcomprising the wild-type TDC1/TDC2 gene and/or a mutant TDC1/TDC2 gene,respectively, in another test sample obtained from the animal over time,wherein a decrease in the level of nucleic acid comprising the wild-typeTDC1/TDC2 gene and/or an increase in the level of nucleic acidcomprising a mutant TDC1/TDC2 gene is indicative of the anti-hearingloss agent being effective, an increase in the level of the nucleic acidcomprising the wild-type TDC1/TDC2 gene and/or a decrease in the levelof the nucleic acid comprising a mutant TDC1/TDC2 gene is indicative ofthe anti-hearing loss agent being ineffective, and no change in thelevel of nucleic acid comprising the wild-type TDC1/TDC2 gene and/or amutant TDC1/TDC2 gene is indicative of no change in the hearing loss dueto treatment with the anti-hearing loss agent.

A mutant transductin gene product also can be detected in a test sampleobtained from an animal and is indicative of hearing loss or apredisposition to hearing loss in the animal. Accordingly, the presentinvention further provides a method for detecting hearing loss or apredisposition to hearing loss in an animal comprising detecting amutant transductin in a test sample comprising protein comprisingtransductin obtained from the animal, wherein the presence of a mutanttransductin in the test sample is indicative of hearing loss or apredisposition to hearing loss in the animal. Examples of suchmutations, which are indicative of hearing loss or a predisposition tohearing loss, have been described above. Thus, the method comprisesdetecting a mutant TDC1/TDC2 in a test sample comprising proteincomprising TDC1/TDC2 obtained from the animal, wherein the presence of amutant TDC1/TDC2 in the sample is indicative of hearing loss, or apredisposition to bearing loss in the animal. The hearing loss can behereditary, sensorineural hearing loss, nonsyndromic autosomal-dominant,and/or DFNA 36-linked hearing loss. The ability of the mutant TDC1/TDC2to form a component of a hair cell of the inner ear of the animal can becompromised. The ability of the mutant TDC1/TDC2 to form all or some ofan on transduction channel of the hair cell of the inner ear of theanimal can be compromised. The mechanosensory activity of the mutantTDC1/TDC2 can also be compromised.

The levels of wild-type TDC1/TDC2 and/or a mutant TDC1/TDC2 also can bedetermined. Accordingly, the invention also provides a method ofdetermining the level of wild-type TDC1/TDC2 and/or a mutant TDC1/TDC2in a test sample comprising protein comprising wild-type TDC1/TDC2and/or a mutant TDC1/TDC2 obtained from an animal. The method comprisesassaying the test sample for the level of wild-type TDC1/TDC2 and/or amutant TDC1/TDC2, wherein a decrease in the level of wild-type TDC1/TDC2and/or an increase in the level of a mutant TDC1/TDC2 in the test sampleas compared to a control sample (as described previously) is indicativeof hearing loss or a predisposition to hearing loss in the animal.

Various assays (i.e., immunobinding assays) are contemplated fordetecting and/or measuring the quantity of wild-type transductin and/ora mutant transductin in a test sample obtained from an animal. Forexample, separate and distinct antibodies can be prepared and employedto detect wild-type transductin and a mutant transductin, respectively.Alternatively, wild-type transductin and a mutant transductin can beutilized to detect antibodies having reactivity therewith. The steps ofvarious useful immunodetection assays have been described, for example,in Nakamura et al., Handbook of Experimental Immunology (4^(th) Ed).,Vol. 1, Chapter 27, Blackwell Scientific Publ., Oxford (1987); Nakamuraet al., Enzyme Immunoassays: Heterogenous and Homogenous Systems,Chapter 27 (1987). Suitable immunoassays include, for example, Westernhybridization (i.e., Western blots), immunoaffinity purification,immunoaffinity detection, enzyme-linked immunosorbent assay (e.g., anELISA), and radioimmunoassay. Moreover, a microarray can be used todetect and/or measure the levels of wild-type transductin and/or amutant transductin in a test sample obtained from an animal.

In general, the immunobinding assays involve obtaining a test samplesuspected of containing a protein, peptide, polypeptide, and/or antibodycorresponding to wild-type transductin and/or a mutant transductin, andcontacting the test sample with one or more antibodies under conditionseffective to allow the formation of immunocomplexes. It is suitable, forexample, to contact concurrently, or sequentially, a test sampleobtained from an animal with an antibody that is specific to wild-typetransductin and with an antibody that is specific to a mutanttransductin.

Any suitable antibody can be used in conjunction with the presentinvention such that the antibody is specific for wild-type transductin.Likewise, any suitable antibody can be used in conjunction with thepresent invention such that the antibody is specific for a mutanttransductin. In particular, suitable antibodies recognize and interactwith (i.e., bind to) one or more portions of wild-type transductin andwith one or more portions of a mutant transductin. Moreover, suitableantibodies include antibodies that recognize and interact with otherantibodies present in a test sample that bind to wild-type transductin.Likewise, suitable antibodies include antibodies that recognize andinteract with other antibodies present in a test sample that bind to amutant transductin. Antibodies for use in the present inventive methodscan be produced by any known technique, e.g., as described inAntibodies: A Laboratory Manual, Cold Spring Harbor Laboratory (1988).

Contacting a test sample comprising a protein comprising wild-typetransductin and/or a mutant transductin with an antibody or antibodiesthat recognize wild-type transductin and/or a mutant transductin underconditions effective, and for a period of time sufficient, to allow forformation of immune complexes (primary immune complexes) is generally amatter of adding the antibody to the test sample and incubating themixture for a period of time long enough for the antibodies to formimmune complexes with wild-type transductin and/or a mutant transductin.Detection of immunocomplex formations can be achieved through theapplication of numerous techniques which are well-known in the art.These detection methods are generally based upon the detection of alabel or marker, such as any radioactive, fluorescent, biological aenzymatic labels of standard use in the art, as described, for example,in U.S. Pat. Nos. 3,817,837, 3,850,752, 3,939,350, 3,996,345, 4,277,437,4,275,149 and 4,366,241. Of course, additional advantages can berealized by using a secondary binding ligand, such as a second antibodyor a biotin/avidin ligand binding arrangement, as is known in the art.

The antibody or antibodies which is/are used in the context of thepresent invention can, themselves, be linked to a detectable label. Sucha detectable label allows for the presence of, or the amount of, theprimary immune complexes to be determined. Alternatively, the firstadded component that becomes bound within the primary immune complexescan be detected by means of a second binding ligand that has bindingaffinity for the first antibody. In these cases, the second bindingligand is, itself, often an antibody, which can be termed a “secondary”antibody. The primary immune complexes are contacted with the labeled,secondary binding ligand, or antibody, under conditions effective andfor a period of time sufficient to allow the formation of secondaryimmune complexes. The secondary immune complexes are then washed toremove any non-specifically bound labeled secondary antibodies orligands, and the remaining label in the secondary immune complexes isthen detected.

Further methods include the detection of primary immune complexes by atwo-step approach. A second binding ligand, such as an antibody, thathas binding affinity for the first antibody is used to form secondaryimmune complexes, as described above. After washing, the secondaryimmune complexes are contacted with a third binding ligand or antibodythat has binding affinity for the second antibody, again underconditions effective and for a period of time sufficient to allow theformation of immune complexes (tertiary immune complexes). The thirdligand or antibody is linked to a detectable label, allowing detectionof the tertiary immune complexes thus formed.

The invention also provides for the use of the method in prognosticatinghearing loss in an animal. The method comprises comparing the level ofwild-type TDC1/TDC2 and/or a mutant TDC1/TDC2 in the test sample to thelevel of wild-type TDC1/TDC2 and/or a mutant TDC1/TDC2, respectively, inanother test sample obtained from the animal over time, wherein adecrease in the level of wild-type TDC1/TDC2 and/or an increase in thelevel of a mutant TDC1/TDC2 is indicative of an unfavorable prognosis,an increase in the level of the wild-type TDC1/TDC2 and/or a decrease inthe level of a mutant TDC1/TDC2 is indicative of a favorable prognosis,and no change in the level of the wild-type TDC1/TDC2 and/or a mutantTDC1/TDC2 gene is indicative of no change in the hearing loss.

The invention also provides for the use of the method in assessing theefficacy of treatment of bearing loss in an animal. The method comprisescomparing the level of wild-type TDC1/TDC2 and/or a mutant TDC1/TDC2 inthe test sample to the level of wild-type TDC1/TDC2 and/or a mutantTDC1/TDC2, respectively, in another test sample obtained from the animalover time, wherein a decrease in the level of the wild-type TDC1/TDC2and/or an increase in the level of a mutant TDC1/TDC2 is indicative ofthe anti-hearing loss agent being effective, an increase in the level ofthe wild-type TDC1/TDC2 and/or a decrease in the level of a mutantTDC1/TDC2 is indicative of the anti-hearing loss agent beingineffective, and no change in the level of the wild-type TDC1/TDC2and/or a mutant TDC1/TDC2 is indicative of no change in the hearing lossdue to treatment with the anti-hearing loss agent.

The invention also provides a method of treating an animalprophylactically or therapeutically for hearing loss (e.g., hearingloss), wherein the hearing loss is due to a complete or partial loss ofwild-type TDC1/TDC2, which method comprises providing TDC1/TDC2 to theanimal, whereupon the animal is treated prophylactically ortherapeutically for hearing loss. Use of the terms “prophylactically,”“prophylaxis,” and derivatives of these terms is not meant to be limitedto absolute prevention of hearing loss, but also less than 100%prevention of hearing loss. The ordinarily skilled artisan willappreciate that a less than 100% prevention of hearing loss may still bebeneficial to an animal, and thus contemplated to be within the scope ofthe present invention. The hearing loss can be hereditary, sensorineuralhearing loss, nonsyndromic autosomal-dominant, and/or DFNA 36-linkedhearing loss. The ability of the mutant TDC1/TDC2 to form a component ofa hair cell of the inner ear of the animal can be compromised. Theability of the mutant TDC1/TDC2 to form all or some of an ontransduction channel of the hair cell of the inner ear of the animal canbe compromised. The mechanosensory activity of the mutant TDC1/TDC2 alsocan be compromised.

Any suitable method can be used for administering or providingtransductin to an animal, wherein the transductin enters the nucleusand/or cytoplasm of one or more hearing loss cells (e.g., one or morehearing loss cells) of the animal and functions within the cell(s) in amanner which is typical of wild-type transductin. For example,transductin can be provided to the animal by administering to the animalthe wild-type transductin protein, or a portion thereof (e.g., two ormore different forms of wild-type transductin). Moreover, transductincan be provided to an animal through administration of a fusion proteincomprising wild-type transductin, or a portion thereof, operably linkedto one or more moieties of interest (e.g., two or more, three or more,four or more, or five or more therapeutic moieties, such as anti-hearingloss agents, and/or any compounds which stimulate transductin). Inanother embodiment, transductin is provided to an animal throughadministration of a nucleic acid encoding and expressing wild-typetransductin, or a portion thereof. Moreover, transductin can be providedto an animal through administration of a nucleic acid encoding andexpressing a fusion protein comprising wild-type transductin, or aportion thereof, operably linked to one or more moieties of interest.The administered nucleic acid can be in any suitable form. For example,the administered nucleic acid can be naked DNA or RNA. Moreover, theadministered nucleic acid can be part of any suitable vector or vectorsystem. Suitable vectors for use in the method include, for example,plasmid vectors, retroviral vectors, adenoviral vectors,adeno-associated viral vectors, vaccinia virus, sindbis virus,cytomegalovirus, herpes simplex virus, defective hepatitis B viruses,and any other vector or vector system known in the art. Fusion proteinsand nucleic acids encoding and expressing fusion proteins can beproduced using any standard methods of recombinant production andsynthesis known in the art, as described, for example, in Sambrook etal., Molecular Cloning: A Laboratory Manual, 2^(nd) Ed., Cold SpringHarbor Press, Cold Spring Harbor, N.Y., 1989.

In view of the above, also provided is a composition. The compositioncomprises (i) a pharmaceutically acceptable carrier and (ii) transductinor a portion thereof; a fusion protein comprising transductin or aportion thereof, operably linked to one or more moieties of interest; anucleic acid encoding and expressing transductin or a portion thereof;and/or a nucleic acid encoding and expressing a fusion proteincomprising transductin or a portion thereof, operably linked to one ormore moieties of interest.

The carrier can be any suitable carrier. Preferably, the carrier is apharmaceutically acceptable carrier. With respect to compositions, thecarrier can be any of those conventionally used and is limited only bychemico-physical considerations, such as solubility and lack ofreactivity with transductin, and by the route of administration. It willbe appreciated by one of skill in the art that, in addition to theabove-described composition, the compositions of the present inventivemethods can be formulated as inclusion complexes, such as cyclodextrininclusion complexes, or liposomes. The pharmaceutically acceptablecarriers described herein, for example, vehicles, adjuvants, excipients,and diluents, are well-known to those skilled in the art and are readilyavailable to the public. It is preferred that the pharmaceuticallyacceptable carrier be one which is chemically inert to transductin andone which has no detrimental side effects or toxicity under theconditions of use.

As is understood in the art, the choice of carrier is dependent onseveral factors, e.g., the type of hearing loss being treated and theroute of administration of the composition. Such a choice of carrier foruse in the composition of the present invention is well within theordinary skill in the art. Accordingly, there are a variety of suitableformulations of the composition of the present invention. Suchformulations include but, are not limited to, oral, aerosol, parenteral,subcutaneous, intravenous, intramuscular, interperitoneal, rectal, andvaginal formulations.

One skilled in the art will appreciate that suitable methods ofadministering a composition of the invention to an animal, in particulara human, are available, and, although more than one route can be used toadminister a particular compound, a particular route can provide a moreimmediate and more effective reaction than another route.

Desirably, gene replacement therapy would be employed to treattherapeutically hereditary deafness in a mammal resulting from amutation or deletion of TDC1 and/or TDC2. Methods of constructingvectors encoding therapeutic genes are known to one of ordinary skill inthe art. Such constructs include viral vectors, preferably adenoviral oradeno-associated viral vectors, naked DNA, plasmid vector, and othergenetic constructs. The vectors can be delivered by any method known inthe art. Ideally, these vectors would be delivered to the animaltranstympanically.

The dose administered to an animal, in particular a human, should besufficient to treat the hearing loss prophylactically ortherapeutically. One skilled in the art will recognize that dosage willdepend upon a variety of factors including the strength of theparticular composition employed, as well as the age, species, condition,and body weight of the animal. The size of the dose will also bedetermined by the route, timing, and frequency of administration as wellas the existence, nature, and extent of any adverse side-effects thatmight accompany the administration of a particular composition and thedesired physiological effect.

Suitable doses and dosage regimens can be determined by conventionalrange-finding techniques known to those of ordinary skill in the art.Generally, a composition is initially administered in smaller dosages,which are less than the optimum dose of the composition. Thereafter, thedosage is increased by small increments until the optimum effect underthe circumstances is reached.

Also provided is a method of identifying one or more agent(s) whichinteract with a mechanotransduction channel of a cell of an animal. Thismethod comprises administering one or more agent(s) to themechanotransduction channel and assaying the mechanotransductionactivity of the mechanotransduction channel, wherein an increase ordecrease in the mechanotransduction activity of the mechanotransductionchannel is indicative of an interaction between one or more agents andthe mechanotransduction channel of the cell of the animal. Preferably,the cell used in the present method would be a hair cell of the innerear of the animal.

The activity of the mechanotransduction can be measured by techniquesknown to one of ordinary skill in the art. For example, the channel ofions across a cell membrane to create a electropotential can be measuredas generally described by Corey et al., Ionic basis of the receptorpotential in a vertebrate hair cell, Nature 281: 675–77 (1979), andHudspeth et al., Sensitivity, polarity, and conductance change inresponse of vertebrate hair cells to controlled mechanical stimuli,Proc. Natl. Acad. Sci. USA 74(6): 2407–11 (1977).

Further provided is a method of identifying one or more agent(s) whichinteract with a TDC1 gene and/or a TDC2 gene in a cell, comprisingadministering one or more agents to the cell comprising the TDC1 geneand/or the TDC2 gene and assaying the expression level of the TDC1 geneand/or the TDC2 gene by the cell as described herein, supra, wherein anincrease or decrease in the expression level of the TDC1 gene and/or theTDC2 gene, as the terms have been described, supra, is indicative of aninteraction between one or more agents and the TDC1 gene and/or the TDC2gene in the cell.

The ordinarily skilled artisan will recognize that several methods ofassaying the expression level of the TDC1 gene and/or the TDC2 geneexist. For example, mRNA can be quantified by a Northern blot analysisusing a polynucleotide synthesized to hybridize to mRNA encoding TDC1and/or TDC2. The polynucleotide can be attached to a probe, or cancontain a radioisotope to facilitate detection of specific hybridizationof mRNA encoding TDC1 and/or TDC2. Alternatively, the level ofexpression of the TDC1 gene and/or the TDC2 gene can also be assayed byquantifying the TDC1 and/or TDC2 polypeptide produced by the cell. Forexample, the cells to which the one or more agents have beenadministered can be contacted with a monoclonal antibody specific toTDC1 or TDC2. Antibody assays for protein are also well-known in the artas described, supra.

While the present invention is described above in the context of hearingloss, it is possible that the present invention has application in thecontext of balance. Indeed, the inner ear is known to comprise twosystems: the auditory system, which is mainly used for audition, and thevestibular system, which functions in maintaining balance andequilibrium of the body. It has been described herein that when theauditory system (i.e., the cochlea) expresses mutant forms of eitherTDC1 and/or TDC2, hearing loss results. It is possible, therefore, thatthe vestibular system, which is responsible for linear and angularacceleration (i.e., balance), can express mutant forms of these genes aswell; however, since the vestibular system controls balance as opposedto audition, it is likely that mutations and/or low expression levels ofthese genes in the vestibular system would result in abnormal balance oreven a complete loss of balance. Thus, the methods of the invention, asthey relate to TDC1 and TDC2, can be carried out with respect to hearingloss and, possibly, abnormal balance or a predisposition to abnormalbalance as well.

EXAMPLE

The following example further illustrates the invention but, of course,should not be construed as in any way limiting its scope.

The following references, to the extent that they provide exemplaryprocedural or other details supplementary to those set forth herein, arespecifically incorporated herein by reference:

-   Birren et al., Genome Analysis: A Laboratory Manual Series, Volume    1, Analyzing DNA, Cold Spring Harbor Laboratory Press, Cold Spring    Harbor, N.Y. (1997),-   Birren et al., Genome Analysis: A Laboratory Manual Series, Volume    2, Detecting Genes, Cold Spring Harbor Laboratory Press, Cold Spring    Harbor, N.Y. (1998),-   Birren et al., Genome Analysis: A Laboratory Manual Series, Volume    3, Cloning Systems, Cold Spring Harbor Laboratory Press, Cold Spring    Harbor, N.Y. (1999),-   Birren et al., Genome Analysis: A Laboratory Manual Series, Volume    4, Mapping Genomes, Cold Spring Harbor Laboratory Press, Cold Spring    Harbor, N.Y. (1999),-   Harlow et al., Antibodies: A Laboratory Manual, Cold Spring Harbor    Laboratory Press, Cold Spring Harbor, N.Y. (1988),-   Harlow et al., Using Antibodies: A Laboratory Manual, Cold Spring    Harbor Laboratory Press, Cold Spring Harbor, N.Y. (1999), and-   Sambrook et al., Molecular Cloning: A Laboratory Manual, 2nd    edition, Cold Spring Harbor Laboratory Press, Cold Spring Harbor,    N.Y. (1989).

Example 1

Mouse and human cochlear cells were lysed, and mRNA transcripts werepurified from the cell lysate. Methods of cell lysis and subsequent mRNApurification are well-known in the art. The Human Genome Projectdatabase was analyzed for the sequences in the human genome thatcorrelated highly with hearing loss in linkage studies. DNA primers wereconstructed from this information using techniques known in the art.These primers were employed in reverse transcriptase-polymerase chainreaction RT-PCR) and 5′- and 3′-rapid amplification of cDNA ends (RACE)on the purified mRNA from cochlear cell lysates. Both methods are alsowell-known in the art. The resulting cDNA molecules were sequenced andidentified as TDC1 and TDC2.

All of the references cited herein are hereby incorporated in theirentireties by reference.

While this invention has been described with an emphasis upon preferredembodiments, it will be obvious to those of ordinary skill in the artthat variations of the preferred compounds and methods may be used andthat it is intended that the invention may be practiced otherwise thanas specifically described herein. Accordingly, this invention includesall modifications encompassed within the spirit and scope of theinvention as defined by the following claims.

1. A method of detecting hearing loss or a predisposition to hearing loss in an animal, which method comprises detecting at least one mutation in a gene encoding TDC1 in a test sample comprising a nucleic acid comprising the TDC1 gene obtained from the animal, wherein the at least one mutation is indicative of hearing loss or a predisposition to hearing loss in the animal.
 2. A method of determining the level of nucleic acid comprising the wild-type TDC1 gene and/or a mutant TDC1 gene in a test sample comprising a nucleic acid comprising the wild-type TDC1 gene and/or a mutant TDC1 gene obtained from an animal, which method comprises assaying the test sample for the level of nucleic acid comprising the wild-type TDC1 gene and/or a mutant TDC1 gene, wherein a decrease in the level of nucleic acid comprising the wild-type TDC1 gene and/or an increase in the level of nucleic acid comprising a mutant TDC1 gene in the test sample as compared to a control sample is indicative of hearing loss or a predisposition to hearing loss in the animal.
 3. The method of claim 2, wherein the method is used for prognosticating hearing loss in the animal, which method further comprises comparing the level of nucleic acid comprising the wild-type TDC1 gene and/or a mutant TDC1 gene in the test sample to the level of nucleic acid comprising the wild-type TDC1 gene and/or a mutant TDC1 gene, respectively, in another test sample obtained from the animal over time, wherein a decrease in the level of nucleic acid comprising the wild-type TDC1 gene and/or an increase in the level of nucleic acid comprising a mutant TDC1 gene is indicative of an unfavorable prognosis, an increase in the level of the nucleic acid comprising the wild-type TDC1 gene and/or a decrease in the level of the nucleic acid comprising a mutant TDC1 gene is indicative of a favorable prognosis, and no change in the level of nucleic acid comprising the wild-type TDC1 gene and/or a mutant TDC1 gene is indicative of no change in the hearing loss.
 4. The method of claim 2, wherein the method is used for assessing the efficacy of treatment of hearing loss in the animal with a given anti-hearing loss agent, which method further comprises comparing the level of nucleic acid comprising the wild-type TDC1 gene and/or a mutant TDC1 gene in the test sample to the level of nucleic acid comprising the wild-type TDC1 gene and/or a mutant TDC1 gene, respectively, in another test sample obtained from the animal over time, wherein a decrease in the level of nucleic acid comprising the wild-type TDC1 gene and/or an increase in the level of nucleic acid comprising a mutant TDC1 gene is indicative of the anti-hearing loss agent being effective, an increase in the level of the nucleic acid comprising the wild-type TDC1 gene and/or a decrease in the level of the nucleic acid comprising a mutant TDC1 gene is indicative of the anti-hearing loss agent being ineffective, and no change in the level of nucleic acid comprising the wild-type TDC1 gene and/or a mutant TDC1 gene is indicative of no change in the hearing loss due to treatment with the anti-hearing loss agent.
 5. A method for detecting hearing loss or a predisposition to hearing loss in an animal, which method comprises detecting a mutant TDC1 in a test sample comprising protein comprising TDC1 obtained from the animal, wherein the presence of a mutant TDC1 in the test sample is indicative of hearing loss or a predisposition to hearing loss in the animal.
 6. A method of determining the level of wild-type TDC1 and/or a mutant TDC1 in a test sample comprising protein comprising wild-type TDC1 and/or a mutant TDC1 obtained from an animal, which method comprises assaying the test sample for the level of wild-type TDC1 and/or a mutant TDC1, wherein a decrease in the level of wild-type TDC1 and/or an increase in the level of a mutant TDC1 in the test sample as compared to a control sample is indicative of hearing loss or a predisposition to hearing loss in the animal.
 7. The method of claim 6, wherein the method is used for prognosticating a hearing loss in the animal, which method further comprises comparing the level of wild-type TDC1 and/or a mutant TDC1 in the test sample to the level of wild-type TDC1 and/or a mutant TDC1, respectively, in another test sample obtained from the animal over time, wherein a decrease in the level of wild-type TDC1 and/or an increase in the level of a mutant TDC1 is indicative of an unfavorable prognosis, an increase in the level of the wild-type TDC1 and/or a decrease in the level of a mutant TDC1 is indicative of a favorable prognosis, and no change in the level of the wild-type TDC1 and/or a mutant TDC1 is indicative of no change in the hearing loss.
 8. The method of claim 6, wherein the method is used for assessing the efficacy of treatment of hearing loss in the animal with a given anti-hearing loss agent, which method further comprises comparing the level of wild-type TDC1 and/or a mutant TDC1 in the test sample to the level of wild-type TDC1 and/or a mutant TDC1, respectively, in another test sample obtained from the animal over time, wherein a decrease in the level of the wild-type TDC1 and/or an increase in the level of a mutant TDC1 is indicative of the anti-hearing loss agent being effective, an increase in the level of the wild-type TDC1 and/or a decrease in the level of a mutant TDC1 is indicative of the anti-hearing loss agent being ineffective, and no change in the level of the wild-type TDC1 and/or a mutant TDC1 is indicative of no change in the hearing loss due to treatment with the anti-hearing loss agent.
 9. A method of identifying one or more agent(s) which interact with a TDC1 gene in a cell, which method comprises administering one or more agent(s) to the cell comprising the TDC1 gene and assaying the expression level of the TDC1 gene by the cell, wherein an increase or decrease in the expression level of the TDC1 gene is indicative of an interaction between one or more agents and the TDC1 gene in the cell. 